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Skyline 1:200 Boeing E3D R.A.F AWACS BOAC

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Skyline 1:200 Boeing E3D R.A.F AWACS BOAC

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Skyline 1:200 Boeing E3D R.A.F AWACS BOAC

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E-3C

Production aircraft with AN/APY-2 radar, additional electronic consoles and system improvements, ten built.

 

Development

 

Background

In 1963, the USAF asked for proposals for an Airborne Warning and Control System (AWACS) to replace its EC-121 Warning Stars, which had served in the airborne early warning role for over a decade. The new aircraft would take advantage of improvements in radar technology which allowed airborne radars to "look down" and detect low-flying aircraft (see Look-down/shoot-down), even over land, which was previously impractical due to ground clutter (see terrain mask). Contracts were issued to Boeing, Douglas and Lockheed, the latter being eliminated in July 1966. In 1967, a parallel program was put into place to develop the radar, with Westinghouse Electric and the Hughes Aircraft being asked to compete in producing the radar system. In 1968 it was referred to as Overland Radar Technology (ORT) during development tests on the modified EC-121Q. The Westinghouse's radar antenna was going to be used by whichever company won the radar competition, since Westinghouse had pioneered in the design of high-power RF phase-shifters.

Boeing initially proposed a purpose-built aircraft, but tests indicated that it would not outperform the already-operational 707, so the latter was chosen instead. To increase endurance, this design was to be powered by eight General Electric TF34s, or carrying its radar in a rotating dome mounted at the top of a forward-swept tail, above the fuselage. Boeing was selected ahead of McDonnell Douglas's DC-8-based proposal in July 1970. Initial orders were placed for two aircraft, designated EC-137D as test beds to evaluate the two competing radars. As the test-beds did not need the same 14-hour endurance demanded of the production aircraft, the EC-137s retained the Pratt & Whitney JT3D commercial engines, and a later reduction in endurance requirement led to retaining the normal engines in production.

The first EC-137 made its maiden flight on 9 February 1972, with the fly-off between the two radars taking place during March–July that year. Favourable test results saw the selection of Westinghouse's radar for the production aircraft. Hughes's radar was initially thought to be a certain winner, simply because much of its design was also going into the new F-15 Eagle's radar program. The Westinghouse radar used a pipelined Fast Fourier Transform (FFT) to digitally resolve 128 Doppler frequencies, while Hughes's radars used analogy filters based on the design for the F-15 fighter. Westinghouse's engineering team won this competition by using a programmable 18-bit computer whose software could be modified before each mission. This computer was the AN/AYK-8 design from the B-57G program, and designated AYK-8-EP1 for its much expanded memory. This radar also multiplexed a Beyond The Horizon (BTH) pulse mode that could complement the pulse-Doppler radar mode. This proved to be beneficial especially when the BTH mode is used to detect ships at sea when the radar beam is directed below the horizon.

 

Full-scale development

Approval was given on 26 January 1973 for full-scale development of the AWACS system. To allow further development of the aircraft's systems, orders were placed for three pre-production aircraft, the first of which performed its maiden flight in February 1975. To save costs, the endurance requirements were relaxed allowing the new aircraft to retain the four JT3D (US Military designation TF33) engines.[6][10] IBM and Hazeltine were selected to develop the mission computer and display system. The IBM computer receiving the designation 4PI, and the software is written in JOVIAL. A Semi-Automatic Ground Environment (SAGE) or BUIC operator would immediately be at home with the track displays and tabular displays, but differences in symbology would create compatibility problems in tactical ground radar systems in Iceland, Europe and Korea over Link-11 (TADIL-A).

Modifications to the Boeing 707 for the E-3 Sentry included a rotating radar dome, single-point ground refuelling, air refuelling, and a bail-out chute. The original design called for two bail-out chutes (one forward, and one aft) but the aft bail-out chute was deleted as a way to cut mounting costs.[11] Engineering, test and evaluation began on the first E-3 Sentry in October 1975. During 1977–1992, a total of 68 E-3s were built.

 

Design

 

Overview

The E-3 Sentry's airframe is a modified Boeing 707-320B advanced model. USAF and NATO E-3s have an unrefuelled range of some 4,000 mi (6,400 km) or eight hours of flying. The newer E-3 versions bought by France, Saudi Arabia and the UK are equipped with newer CFM56-2 turbofan engines, and these can fly for about 11 hours or about 5,000 mi (8,000 km). The Sentry's range and on-station time can be increased through air-to-air refuelling and the crews can work in shifts by the use of an on-board crew rest and meals area.

When deployed, the E-3 monitors an assigned area of the battlefield and provides information for commanders of air operations to gain and maintain control of the battle; whilst as an air defence asset, E-3s can detect, identify and track airborne enemy forces far from the boundaries of the U.S. or NATO countries and can direct fighter-interceptor aircraft to these targets. In support of air-to-ground operations, the E-3 can provide direct information needed for interdiction, reconnaissance, airlift and close-air support for friendly ground forces.

 

Avionics

The unpressurized dome is 30 feet (9.1 m) in diameter, six feet (1.8 m) thick at the centre, and is held 11 feet (3.4 m) above the fuselage by two struts. It is tilted down 1° at the front to reduce its air drag during take-offs, and while flying endurance speed (which is corrected electronically by both the radar and SSR antenna phase shifters). The dome uses both bleed air and cooling doors to remove the heat generated by electronic and mechanical equipment. The hydraulically rotated antenna system permits the Westinghouse Corporation's AN/APY-1 and AN/APY-2 passive electronically scanned array radar system to provide surveillance from the Earth's surface up into the stratosphere, over land or water.

Other major subsystems in the E-3 Sentry are navigation, communications, and computers. Consoles display computer-processed data in graphic and tabular format on video screens. Console operators perform surveillance, identification, weapons control, battle management and communications functions. The radar and computer subsystems on the E-3 can gather and present broad and detailed battlefield information. This includes position and tracking information on enemy aircraft and ships, and location and status of friendly aircraft and naval vessels. The information can be sent to major command and control centres in rear areas or aboard ships. In times of crisis, data can be forwarded to the National Command Authority in the U.S. via RC-135 or naval aircraft carrier task forces.

Electrical generators mounted on each of the E-3's four engines provide the one megawatt of electrical power that is required by the E-3's radars and other electronics. Its pulse-Doppler radar has a range of more than 250 mi (400 km) for low-flying targets at its operating altitude, and the pulse "over-the-horizon radar" radar has a range of approximately 400 mi (650 km) for aircraft flying at medium to high altitudes. The radar combined with a secondary surveillance radar to provide a look down to detect, identify and track enemy and friendly low-flying aircraft while eliminating ground clutter (radar) returns.

 

Operational history

 

In March 1977 the 552nd Airborne Warning and Control Wing (now the 552d Air Control Wing) at Tinker AFB, Oklahoma received the first E-3 aircraft. The 34th and last USAF Sentry was delivered in June 1984. In March 1996, the USAF activated the 513th Air Control Group (513 ACG), an ACC-gained Air Force Reserve Command (AFRC) AWACS unit under the Reserve Associate Program. Collocated with the 552 ACW at Tinker AFB, the 513 ACG which performs similar duties on active duty E-3 aircraft shared with the 552 ACW.

The USAF have a total of thirty-one E-3s in active service. Twenty-seven are stationed at Tinker AFB and belong to the Air Combat Command (ACC). Four are assigned to the Pacific Air Forces (PACAF) and stationed at Kadena AB, Okinawa and Elmendorf AFB, Alaska. One aircraft (TS-3) was assigned to Boeing for testing and development (retired/scrapped June 2012).

In 1977 Iran placed an order for ten E-3's, however this order was cancelled following the 1979 revolution.

NATO acquired 18 E-3As and support equipment for a NATO air defence force. Since all aircraft must be registered with a certain country, the decision was made to register the 18 NATO Sentries with Luxembourg, a NATO member that previously did not have any air force. The first NATO E-3 was delivered in January 1982. The eighteen E-3s were operated by Number 1, 2 and 3 Squadrons of NATO's E-3 Component, based at NATO Air Base Geilenkirchen. Presently 17 NATO E-3As are in the inventory, since one E-3 was lost in a crash.

The United Kingdom and France are not part of the NATO E-3A Component, instead procuring E-3 aircraft through a joint project. The UK and France operate their E-3 aircraft independently of each other and of NATO. The UK operates six aircraft (with a seventh now retired)[28] and France operates four aircraft, all fitted with the newer CFM56-2 engines. The British requirement came about following the cancellation of the British Aerospace Nimrod AEW3 project to replace the Avro Shackleton AEW2 during the 1980s. The UK E-3 order was placed in February 1987, with deliveries starting in 1990. The other operator of the type, delivered between June 1986 and September 1987, is Saudi Arabia which operates five aircraft, all fitted with CFM56-2 engines, This particular sale was hotly contested between the Reagan administration and opponents of the saleE-3 Sentry aircraft were among the first to deploy during Operation Desert Shield, where they immediately established as an around-the-clock radar screen to defend against Iraqi forces. During Operation Desert Storm, E-3s flew 379 missions and logged 5,052 hours of on-station time. The data collection capability of the E-3 radar and computer subsystems allowed an entire air war to be recorded for the first time in history. In addition to providing senior leadership with time-critical information on the actions of enemy forces, E-3 controllers assisted in 38 of the 41 air-to-air kills recorded during the conflict. NATO and RAF E-3s participated in the international military operation in Libya.

On 27 January 2015, the RAF deployed an E-3D Sentry to Cyprus in support of U.S.-led coalition airstrikes against Islamic State militants in Iraq and Syria. The Sentry joins RAF Panavia Tornado, MQ-9 Reaper, and AirTanker Voyager aircraft performing or supporting almost daily strikes against militants.

Additional Information

Show on Homepage Diecast
Diecast Toy Manufacturer Skyline
Manufacturer No
Country United States
Scale 1:200
Type Jet Aircraft
Series No
Color Multi-Colored